1. Field of the Invention
The present invention relates to a preferably integrated circuit configuration provided for the actuation of power switches disposed in bridge circuit topology as well as an associated method. More specifically, the present invention relates to bridge configurations of power switches known as semi-, H- (two-phase) or as three-phase bridge circuits, the single phase semibridge representing the basic module of such electronic power circuits, wherein in a semibridge circuit, two power switches, a first, so-called TOP switch, and a second, so-called BOT switch, are connected in series. As a rule, such a semibridge is connected to a direct current link and the center tapping is typically connected to a load.
2. Description of the Related Art
To place the present invention in relative context, when the power switches are implemented as a power semiconductor component or as a multiplicity of identical series- or parallel-connected power semiconductor components, an actuation circuit is necessary for the actuation of the power switches. Within the related art such actuation circuits are comprised of several subcircuits or function blocks. The actuation signal from a superordinate control is processed in a first subcircuit of the primary side, and, via further components, supplied to the driver circuits, the secondary sides and lastly to the control input of the particular power switch. In semibridge configurations with higher link voltages, for example greater than 50 V, the primary side, in potential/electrical terms, is isolated from the secondary side for the processing of the control signals, since the power switches, at least the TOP switch of the semibridge, during operation are not at a constant potential and consequently the isolation in terms of voltage is unavoidable. This isolation according to the related art takes place for example by means of isolating transformers, optocouplers, for example optical wave guides. This electrical isolation is at least carried out for the TOP switch, but at higher powers also for the BOT switch due to a possible breaking of the ground reference potential during the switching.
The related art also involves known integrated circuit configurations for power switches of the voltage classes up to 600 V or 1200 V, which forgo the use of external electrical isolation. In these monolithically integrated circuits, according to the related art, so-called level shifters are utilized, at least for the TOP switch. These electronic components and techniques for isolation consequently overcome the potential difference of the primary side with respect to the secondary side.
Referring now to FIG. 1, depicted is a circuit configuration for the actuation of power semiconductor switches in bridge topology according to the related art. For the purpose of simplification only one semibridge is shown. Further bridge topologies are analogous hereto.
In the actuation of power semiconductor components 50, 52, such as for example IGBTs (Insulated Gate Bipolar Transistor) in a circuit configuration in bridge topology, isolation of the potential is necessary due to the voltage difference between the superordinate control 10, for example in the form of a microcontroller 10, and the primary side 20 of the circuit configuration on the one hand, and the secondary side 30, 32 of the circuit configuration and the power semiconductor component 50, 52 on the other hand. According to the related art, various feasibilities for potential isolation are known, for example transformers, optocouplers, optical wave guides or electronic components with appropriate electrical strength.
In the monolithic integration of primary side and secondary side, level shifters are frequently utilized for the transmission of control signals from the primary side to the secondary side. With said components for the potential isolation, switch-on and switch-off signals can be transmitted from the primary side (low voltage side) to the secondary side (high voltage side). Essential for the trouble-free operation of an electronic power system is the primary-side information about operating states of the secondary side, for example information about the concrete switched states of the TOP and of the BOT switch or various error conditions.
Such status polling according to a signal transmission from the secondary to the primary side in the case of hybrid solutions is possible by means of transformers, bi-directional optocouplers or bi-directional optical wave-guides. For monolithically integrated solutions, complementary level shifters, preferably utilizing pMOS high-voltage transistors, are known. Of disadvantage in all of said solutions is that an additional signal path with additional costs and/or additional technology expenditures has to be realized.
In view of the above, those of skill in the art will recognize that what is not appreciated by the related art is that in this described form of a monolithically integrated circuit configuration for actuating power switches no possibility exists, at least in the simplest configuration for the secondary side of the TOP switch, for error feedback to the primary side.
Accordingly, there is a need for an improved monolithically integrated circuit configuration for actuating power switches that responds to this detriment.